G.SHDSL was standardized in February 2001 internationally by ITU-T with recommendation G.991.2.

G.SHDSL features symmetrical data rates from 192 kbit/s to 2,304 kbit/s of payload in 64 kbit/s increments for one pair and 384 kbit/s to 4,608 kbit/s in 128 kbit/s increments for two pair applications. The reach varies according to the looprate and noise conditions (more noise or higher rate means decreased reach) and may be up to 3,000 meters.
The two pair feature may alternatively be used for increased reach applications by keeping the data rate low (halving the data rate per pair will provide similar speeds to single pair lines while increasing the error/noise tolerance).

In Europe, a variant of G.SHDSL was standardized by ETSI using the name 'SDSL'. This ETSI variant is not compatible with the ITU-T G.SHDSL standardized regional variant for Europe and must not be confused with the usage of the term 'SDSL' in North America.

The latest standardization efforts (G.SHDSL.bis) tend to allow for flexibly changing the amount of bandwidth dedicated to each transport unit to provide 'dynamic rate repartitioning' of bandwidth demands during the uptime of the interface and optionally provides for 'extended data rates' by using a different modulation method (32-TCPAM instead of 16-TCPAM, where TCPAM is Trellis-Coded Pulse Amplitude Modulation). Also, a new payload type is introduced: packet based, e.g. to allow for Ethernet-frames to be transported natively. (Currently, they may only be framed in ATM or T1/E1/...).
G.SHDSL.bis can deliver a minimum of 2 Mbit/s and a maximum of 5.69 Mbit/s over distances of up to 2.7 km (9 Kft).